The chemistry and biology of two proteins specific to the nervous system are being studied as one approach to neural function. The S-100 protein is glial-specific, exists in multiple forms, binds Ca++ and undergoes a conformational change, and binds to membranes in the presence of Ca++. The aim is to relate these specific properties of S-100 to its function. The 14-3-2 protein is neuronal-specific, has a large repeat sequence in its primary structure and, like S-100, is present in all vertebrate brains. These two proteins are also being used as specific markers for neurons and glia in studying nervous system development, degeneration and disease. The composition and organization of polypeptides of synaptic plasma membranes and of synaptic vesicles is being investigated in order to establish the role of these components in synaptic function, particularly in the relation between synaptic membranes and vesicles during transmitter release, the effects of Ca++ and of depolarization of the plasma membrane, and any effects of S-100 on synaptic plasma membranes. Attempts will be made to purify certain polypeptides and glycoproteins from synaptic membranes, chosen by virtue of their orientation, their being affected by Ca++ or K+, or by specificity to synaptic membranes or vesicles. Chemical, biological and immuno-chemical properties of these proteins will be investigated in relation to functions.